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BT Infinity FTTC (and my own FreeBSD router)

13th Jan 2013, 17:22:17

By James Stocks

Since it was launched three years ago in 2010, BT Infinity with its 80Mb download and
20Mb upload has been a tempting prospect, but the idea of dealing with BT retail horrifies
me. However, having just acquired a building with no phone line, my hand was forced. It
seems BT is the only telecom operator who will install a PSTN line for free for new
subscribers. This saving of £130.00 pushed me over the edge. How bad could it be?

Six weeks(!) after placing an order, BT scheduled an Infinity engineer in the same time
slot as the PSTN engineer, but in a stroke of good fortune they turned up
in the right order. I should have been sent a welcome pack and a Home Hub router
before the arrival of the Infinity engineer, but none was delivered. Thankfully, the
engineer had a spare Home Hub in his van, silly really, since I had no intention of using
the BT-provided router anyway. Nevertheless, by lunchtime, I'd been left with an
openreach modem and a BT Home Hub 3.0 connected to a working BT Infinity service.

I couldn't decipher what the Home Hub was doing based on its incredibly simplistic web
interface, there certainly didn't seem to be any way to turn it into a bridge so I could
use my own router and given the Home Hub's reputation for terrible reliability I had
little inclination to pursue the matter. I'm not really one to trust telco-provided black
boxes anyway. I decided it would be easier to just sniff the packets between the Home
Hub and the openreach box. Lots of PPPoE traffic was what I saw. A quick web search
revealed that a username of bthomehub@btbroadband.com and any password is sufficient
to bring up a PPPoE connection. Good!

I disconnected the Home Hub and plugged in an Alix 2d3 running FreeBSD 9.

My FreeBSD box is on the other end of the network socket connected to the
OpenReach box with the yellow-booted cable, which is just a straight
patch cable.

With the
openreach-provided Huawei HG612 already configured to act as a bridge, it's
now quite straightforward to get FreeBSD to do the PPP connection:

# vi /etc/ppp/pppd.conf
infinity:
# Replace vr2 with the interface connected to the VDSL2 modem
set device PPPoE:vr2
set speed sync
set mru 1492
set mtu 1492
set ctsrts off
enable echo
set echoperiod 15
enable lqr
set lqrperiod 15
set log Phase tun
enable ipcp
disable dns
# Replace vr2 with the interface connected to the VDSL2 modem
set server /tmp/pppoe-vr2 "" 0177
set authname bthomehub@btbroadband.com
set authkey BT
# HISADDR is shorthand for the remote end of the link,
# pppd will set this as the default route
add! default HISADDR

The indenting is important and forms part of the config file syntax! A quick tweak to
rc.conf is needed to bring up the PPP connection on boot: